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Report MST zOzz-av sod RECEIVE:' : DEC 0 5 T. CITY OF TIGAt;v S O L G N BUILDING DIVISION POWER July 20, 2022 Subject: Proposed Solar Panel Installation Marshall Clark Residence, 11630 SW Lomita Ave,Tigard,OR To Whom it May Concern, Our engineering department has reviewed information,gathered by our field crews, related to the proposed solar panel installation at the above-referenced address. The purpose of our review was to determine the structural adequacy of the existing roof. Based on our review and analysis of the available information, and in accordance with governing building codes, it is our professional opinion that the existing structure is permitted to remain unaltered for the proposed solar installation. Design Parameter Summary Governing Building Code:2019 Oregon Structural Specialty Code (2019 OSSC) Risk Category: II Design Wind Speed: 110 mph (per ASCE 7-16) Ground Snow Load: 11 psf Roof Information Roof Structure:2x4 Manufactured Trusses @ 24"O.C. Roofing Material:Asphalt Shingles(1 layer) Roof Slope:23 degrees Roof Connection Details RT Minis into 2x rafters or truss top chords at 48"O.C., install per design drawings and manufacturer specs Locations per design drawings Note:Required embedment length excludes the tapered tip of the screw,and embedment into sheathing. Analysis The proposed installation -including weight of panels, racking, and mounts -will be approximately 2.62 psf. In the areas where panels are installed, roof live loads will not be present.The reduction of roof live load is adequate to fully or partially compensate for the addition of the panel installation. Because the member forces in the area of the solar panels are not increased by more than 5%, the stresses in the members are not increased by more than 5%,and so per section 3408.6.2 of the 2019 OSSC(IEBC Section 806.2),the structure need not be altered for gravity loading. The proposed installation will be 6" max. above the roof surface (flush mounted) and parallel to the roof surface. Therefore, any increase in wind loading on the building structure from the solar panel installation is expected to be negligible. Wind is the governing lateral load case. Because the increase in lateral loading is not increased by more than 10%,per section 3408.6.3 of the OSSC(IEBC 806.3),the structure need not be altered for lateral loading. Wind uplift on the panels has been calculated in accordance with the relevant provisions of ASCE 7-16.This loading has been used to verify the adequacy of the connection specified above. Connection locations should be in accordance with design drawings. Conclusion The roof structure need not be altered for either gravity or lateral loading. Therefore, the existing structure is permitted to remain unaltered. Connections to the roof must be made per the "Roof Connection Details" section above. Copies of all relevant calculations are enclosed. Limitations and Disclaimers The opinion expressed in this letter is made in reliance on the following assumptions: the existing structure is in good condition; the existing structure is free from defects in design or workmanship;and the existing structure was code-compliant at the time of its design and construction. These assumptions have not been independently verified, and we have relied on representations made by the property owner and his or her agents with respect to the foregoing.The undersigned has not inspected the structure for patent or latent defects. Electrical engineering is beyond the scope of this analysis. Solar panels must be installed per manufacturer specifications. Structural design and analysis of the adequacy of solar panels, racks, mounts, rails, and other components is performed by each component's respective manufacturer and the undersigned makes no statement of opinion regarding such components. This letter and the opinions expressed herein are rendered solely for the benefit of the permitting authority(city or county building department), and may not be utilized or relied on by any other party. If you have any questions or concerns, please contact our office at (855)-709-1181, or email me directly at Trevor.Jones@solgenpower.com. Sincerely, Trevor A.Jones, P.E. iR6,a PROP( �i}> ss ;p4'OR Dv. EXPIRES: 06/30/23 7/20/2022 RECE#VI._ DEC 0 ) ;.?C':''? 1 CITY OF TIC,,r t S O L G N BUILDING DIVISION pow ER Note: All calculations per ASCE 7 Load Comparison This calculation justifies the additional solar load by comparing existing to proposed gravity loads in the location of the solar panels. Without Solar With Solar Dead Load Asphalt Shingles 3 3 psf 1/2" Plywood 1 1 psf Framing 3 3 psf Insulation 1 1 psf 1/2" Gypsum Ceiling 2 2 psf M,E, & Misc 1.5 1.5 psf Solar Panel 0 2.62 psf Total Dead Load 11.5 14.12 psf Snow Load Ground Snow Load, Ps 11 psf Exposure Factor, Ce 1 Thermal Factor, Ct 1.1 Importance Factor, IS 1 Flat Roof Snow Load _ Eqn. 7.3-1 or jurisdiction min. Slope 23 degrees Unobstructed Slippery Surface? Slope Factor, CS 1.00 1.00 Sloped Roof Snow Load 8.5 8.5 psf Live Load Roof Live Load 20 0 psf Load Combination D+ Lr 31.5 14.1 psf D + S 20.0 22.6 psf Max. Load 31.5 22.6 psf %of original 72% Result: Because the total forces are decreased, per the relevant code provisions stated in the body of the letter, the existing roof structure is permitted to remain unaltered. 1 SOLGEN POWER RT Mini Connection Calculation This calculation justifies the connection of the solar panels to existing roof members, by showing the connection capacity is equal to or greater than the uplift force demands. Connection Demand Spacing perpendicular to rail in 1/2 panel length Spacing parallel to rail in Max spacing Effective Wind Area on each connection 10.8 ft` Roof Angle 23 degrees sw R / - Wind Speed 110 mph I.FOOT Exposure Coefficient, lc = /11o� Topographic Factor, Kip 1 ROOMINI 1 F nem -y,., . NO Directionality Factor, Kd 0.85 >rNO Elevation Factor, Ke 0.99 `, Velocity Pressure,qz 22.2 psf Mu exIsdr tl mol et�.NYq -'--'�^ / Mo erlstlry ref0.2 Zone 1 Zone 2r Zone 3 GCp(max) 1.90 1.97 1.97 Exposed Panels?(yE=1.5) Pressure Equalization Factor,ya 0.79 0.79 0.79 Uplift Force 33.1 34.5 34.5 psf Max. Uplift Force/Connection(1.0 WL) 358.7 373.2 373.2 lbs ASD Factored(0.6 WL) 215.2 223.9 223.9 lbs Solar Dead Load(0.6 DL) 17.0 17.0 17.0 lbs Max. Uplift Force(0.6 WL-0.6 DL) 198.2 206.9 206.9 lbs Connection Capacity Connection Type RT Mini into 2x Rafter Total Allowable Capacity 447.0 lbs (per manufacturer) Compare ASD Factored Demand to Capacity Demand 206.9 lbs Capacity 447.0 lbs Result Capacity exceeds demands.Therefore,connection passes.